inbreeding/linebreeding

Question
why is linebreeding i.e. mother/son and father/daughter ok but brother sister is not advisable would it be that the genes of siblings are an exact match and this could cause problems, whereas parents don't have exact match? is it better to outbreed? i have three kittens from unrelated pair. they are all different in appearance and i dont know whether to just let the mum and dad have a further litter. also. . . the doe was great with her babies and she was 6 months. i've been reading about expecting sleepless nights etc. apart from modifying the hutch to stop the kittens from coming out of the night bit too early or then falling off the ramp it wasn't that stressful. they all seem healthy and happy. have i overlooked something

Answer
hi tracey -i would always use unrelated rabbits as line breeding can produce rabbits that to be quite frank are mad .
i have sen some that were line bred and they were very hard to control they bite and fight .
if as you say the adults are unrelated , go ahead and breed again.
your cage seems ok and i dont think you have done anything wrong.
dave.